Definition 1.2 [1]}
Let \(S\)  be a set of distinct elements of \(\mathbb {C}\cup \lbrace \infty \rbrace \)  and \(k\)  be a non-negative integer or \(\infty \) . We denote by \(E_{f}(S,k)\)  the set \(\bigcup _{a\in S}E_{k}(a,f)\) .
